1. Field of the Invention
The present invention relates to a motor control method for controlling a drive motor and a print apparatus.
2. Description of the Related Art
A print apparatus includes a plurality of drive motors, a power source, a conveyance roller, a carriage that reciprocates, and the like. Conventionally, a pulse width modulation control (PWM control) has been generally used for a motor for driving each unit mechanism. In order to stop the drive motor in the case of contingencies such as jamming during conveyance, a PWM duty of the drive motor is monitored. Furthermore, in order to protect the power source in the case where a current value of the power source becomes abnormally high, a power source protection circuit is provided.
Japanese Patent Laid-Open No. 2009-73606 discloses a control method for stopping the drive motor before the power source is shut down, in the case where the PWM duty of a previously set threshold value or more is detected for a predetermined time or longer.
In the case where a plurality of motors is driven simultaneously by a single power source, the power source comes to have no margin with an increase in load of an entire apparatus particularly during acceleration, a voltage drop is generated, and thus a motor output is lowered. In the case of increasing the PWM duty for accelerating the motor in order to compensate for the lowered motor output, there are cases where the PWM duty exceeds the set threshold value and thus the motor cannot be correctly stopped.
Furthermore, in the case where the occurrence of jamming cannot be detected in an early stage, the power source protection circuit may be operated to thereby shut down the power source before stopping the motor. Once the power source is shut down, it takes a long time to recover, and thus a user cannot perform printing during the recovery.